UPDATE 3-IBM to buy marketing software co Unica

* IBM to pay about $21 per Unica share

* Unica shares price more than doubles to $20.75

* Unica specializes in marketing software

* Deutsche advised IBM, Jefferies advised Unica

* Unica shares up 117 percent to $20.75 (Adds Deutsche Bank and Jefferies as advisers, share prices, Unica customers)

NEW YORK, Aug 13 (Reuters) - IBM (IBM.N) said on Friday it will buy marketing software firm Unica Corp UNCA.O for about $480 million in cash to expand its business software and technology services, sending Unica shares up 117 percent.

IBM, which recently said it would buy more companies to move further into software and services, will pay around $21 per Unica share, a premium of about 120 percent from Thursday's close.

Unica shares rose as high as $20.78 in morning trading on the Nasdaq stock market.

IBM said Unica will boost its ability to help companies analyze and predict customer behavior and develop better marketing. Unica's 500 employees will join IBM's software solutions group.

Deutsche Bank (DBKGn.DE) advised IBM; Jefferies (JEF.N) advised Unica.

The acquisition, which requires Unica shareholder approval and regulatory clearance, would close in the fourth quarter of 2010, the companies said.

Unica has more than 1,500 customers in the financial services, insurance, retail telecommunications, travel and hospitality businesses. Customers include Best Buy (BBY.N), eBay (EBAY.O) and ING (ING.AS).

IBM plans to spend $20 billion buying assets over the next five years to move into higher-margin businesses and away from increasingly commoditized hardware sales.

Its recent acquisitions include privately held Datacap, which helps companies digitize paper documents. It did not say how much it paid.

In May, it said it would pay $1.4 billion for Sterling Commerce, which specializes in secure transfers of electronic documents like payroll and healthcare claims.

The acquisitions come as rivals Hewlett-Packard Co (HPQ.N), Oracle Corp (ORCL.O) and Dell (DELL.O) scour the markets for deals as they compete to offer more products and services. (Reporting by Ritsuko Ando, additional reporting by Soyoung Kim; Editing by Derek Caney and Robert MacMillan)